COMP: Eliminate some level 4 warnings

When building our project with level 4 warnings and the Visual Studio 2012
compiler, we were getting several C4701 ("potentially uninitialized local
variable") and C4702 ("unreachable code") warnings.

This commit eliminates those warnings.

Change-Id: Idc35e8de30c80a19d1a961bb17b1a865a46c0612
COMP: Do not use -fno-ipa-cp-clone with clang.

The flag is only known to have issues with GCC 4.8.2.  Disable for clang to
avoid the warning:

  clang: warning: argument unused during compilation: '-fno-ipa-cp-clone'

Change-Id: If81b65d315b43d342ffa430fa17a202f19305b7c
Merge topic 'clang-no-ipa-cp-clone'

ac0d3d71 COMP: Do not use -fno-ipa-cp-clone with clang.
BUG: Return null pointer if class label does not exist (#3235)

When GetClassSample() method is called, it looks up the internal index
of the given class label, but does not consider whether the label exists
or not. If the label does not exist, -1 will be used as the internal
index and an invalid pointer is returned. In addition, it is not
possible to check whether a particular class label exists or not. By
returning null for non-existent class labels, both issues are addressed.

Change-Id: I3c4c5b40267318a7e6d5cf7c6f55cb00cea38aab
Merge topic 'getclasssample-fix'

6c012a6e BUG: Return null pointer if class label does not exist (#3235)
Merge topic 'eliminate-some-level-4-warnings'

43efb178 COMP: Eliminate some level 4 warnings
ENH: Bump ITK version to 4.5.1.

Change-Id: Id795e74bd0d861f69698a8c1b04a0f99d9a74e54
Merge branch 'release'

Conflicts:
	CMakeLists.txt

Change-Id: I37e4b3a41f765fed256f13e6ae483899e2a3494c
COMP: ImageRegistrationHistogramPlotter Clone never referenced.

For:

  /scratch/dashboards/Linux-x86_64-icc13/ITK/Examples/Registration/ImageRegistrationHistogramPlotter.cxx(394):
  warning #177: function "<unnamed>::CommandIterationUpdate::Clone" was
  declared but never referenced

Change-Id: I1d53d34b221132c76b1638e00e1ce9d5be47f730
STYLE: Removed deprecated itk functions

Those 3 functions were marked as deprecated (seems to come from ITK 3, but was never cleaned up in the python wrappings)
physical_point_to_index
physical_point_to_continuous_index
index_to_physical_point
Merge topic 'deprecated-python-functions'

281b8f59 STYLE: Removed deprecated itk functions
Merge topic 'histogram-icc'

d67d2223 COMP: ImageRegistrationHistogramPlotter Clone never referenced.